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The Hudson-Raritan Estuary and the New Jersey Atlantic Ocean shoreline are densely-populated regions that provide significant economic environmental and recreational benefits to the States of New York and New Jersey and to the US nation. Issues confronting the region include safe navigation and maritime security within one of the largest ports in the world water quality concerns and beach erosion and flooding along the heavily-populated New Jersey and Long Island shorelines. Since 1998 Stevens has been developing a network of operational coastal ocean and estuary sensors that provide realtime observations of weather and ocean conditions throughout the region.As the network has expanded and experience has been gained in the operation of the sensors and in the specialised needs of the array of data users the system has evolved significantly. A forecasting component has been added and 48-hour forecasts of weather and ocean conditions throughout the region are provided via the Internet. The modelling system is based on a high-resolution version of the Princeton Ocean Model. The model employs advanced data assimilation algorithms in order to optimise the use of the real-time ocean and weather data in the forecasting system.

The sediment in mangrove swamps is highly impermeable and therefore greatly impedes the transport of porewater solutes. Subterranean animal burrows provide an alternative pathway by which porewater can be conveyed to and from deep within the mangrove substrate. Burrows have been observed to penetrate up to 1.2 m and greater into the mangrove sediment. Subterranean burrows in mangrove swamps may be located in situ by use of an electronic probe. An array of ring electrodes mounted on a rod provides an effective means of measuring the apparent electrical conductivity in sediment. The variations in the conductivity indicate different sediment characteristics. The probe is used to locate voids in the sediment; i.e. burrows formed by animals. One the burrows have been located samples of the burrow water are extracted for testing. The concentrations of dissolved nitrogenous compounds and of salt are determined to investigate the tidal flushing of the burrows. The concentrations of nitrogen-based solutes compare favourably with previous studies and show little variation with depth. The salinity data support the hypothesis that significant mixing of burrow water occurs throughout the entire depth of the burrow. Methods are described and results are presented.

The raising of the Mary Rose in 1982 made headline news. As an archaeological event it ranked alongside Schliemanns excavations at Troy or Arthur Evanss discovery of Knossos, and so much information has since been gleaned from the wreck and its contents that there is an overwhelming tendency to treat the ship as a "time-capsule", like some Tudor burial site. But the Mary Rose is not just an archaeological relic. She is a warship that was revolutionary in her time and, despite being most famous for her loss in battle, a ship that had served her monarch for 34 years, almost the length of his reign. This book tells the full story of the construction and career of the ship, placing it firmly within the colorful context of Tudor politics, court life and the developing administration of a permanent navy. However, it also brings the story down to the present day, with chapters on the recovery and the new ideas and information thrown up by the massive program of archaeological work since undertaken. Written by the Development Director of The Mary Rose Trust and heavily illustrated from the massive resources of the Trust, this is a book which will appeal to general reader and specialist alike.

The assembly process in shipbuilding essentially involves the joining of large blocks. These blocks are typically all-welded thin plate structures. During the fabrication of these blocks distortions occur due to a variety of causes including the cutting and the welding. Even through it is practically impossible to eliminate distortion completely it is necessary to produce blocks with a sufficient level of accuracy so as to avoid problems in the course of assembly. Local shrinkage is produced as an unavoidable consequence of welding. While this shrinkage is the major cause of the geometrical error in the welded structure there are many other contributing factors that cannot be ignored such as initial geometrical error in the parts root gap of the groove positioning and fixture prior to welding. The welding sequence is one of the major contributing factors to the root gap and the misalignment and hence to geometrical accuracy. Generally there are two major causes of geometrical error in the welded structure. The first cause is local shrinkage due to the thermal cycle experienced in the weld zone. The local distortion can be divided into three categories namely longitudinal shrinkage transverse shrinkage and angular distortion. All three types are strongly affected by heat input shape of penetration plate thickness and joint type. The second cause is the gap and the misalignment produced in the joint prior to welding. Contributing factors on the gap and the misalignment are the welding sequence

Intermittent riser VIV behaviour caused by vessel motions can affect both riser strength and fatigue life. Frequency domain codes are available that are used routinely to calculate riser fatigue damage from VIV due to currents. These codes are often adapted to calculations of the vessel motion VIV and fatigue damage. The adaptations reduce the intermittent VIV to steady state VIV by assuming an appropriate time invariant velocity profile over the length of the riser. However since vessel motions cause a relative velocity profile over the riser that varies with time and the VIV response is intermittent a time domain VIV code is best suited for such an analysis. The use of Technip's time domain riser VIV code ABAVIV is demonstrated to calculate steel catenary riser VIV response and fatigue damage due to vessel motions. Since time domain analysis is computer-time intensive an efficient methodology to perform these calculations is also outlined. The analysis example in the paper is based on surge pitch and heave motions which are the most important vessel motions for the riser fatigue damage near the touch down region. The ABAVIV code accounts for the non-linear structural characteristics of the SCR and the unsteadiness of the VIV phenomenon for the present application.

A trimaran concept for offshore operations has been developed. Vessel features include low response in waves low resistance for efficient transfer over long distances launching positions for intervention equipment and a large deck area. The vessel may in different versions represent an interesting design to be used for field development and for inspection maintenance and repair in Northern Seas. Efficiency in operation has been focused on in the development of this concept. To build a vessel for the future one has to study where the industry is moving and where likely work will be coming up in the future. Advances in technology both in ship design and in subsea intervention are hard to predict and the capacities and characteristics for the future are hard to foresee. Some characteristics are however likely to be desired in the future as well. These are characteristics such as low vessel motions good fuel economy a large deck area and high loading capacity to name but a few. These characteristics are in turn perhaps not easy to combine. One vessel concept that combines some of these features in an elegant way is the trimaran. Concept development and theoretical analysis were followed up with tank testing. A 1:50 scale model was built and tested in a 60 m towtank. Resistance and Motion tests were carried out and compared with computer analysis. Comparison of results shows good consistency between analysis and tank tests.

There has been a global drive for renewable energy research and development. There are a number of renewable energy sources: wind power solar hydrogen electric geothermal biomass and marine energy. Tidal energy is a form of hydropower which concerts the energy in the tide into electricity. Tidal energy systems can further classified into two groups: tidal barrages which make use of the potential energy in the different in height between the high and low tides and tidal current systems which make use of the kinetic energy in the ebb and flood flow to drive the turbines. Tidal current energy conversion is reliable and has minimal negative environmental impact is cheap and continuous and is not weather-dependent. Scottish enterprise has estimated that about 34% of UK electricity demand can be produced from tidal currents; this signifies a huge untapped resource. A typical tidal current energy system is a simple system comprising a tidal turbine supported on a structure positioned to extract the kinetic energy of the ebb and flow of the tides. An electrical grid connected system allows for the supply of electricity to consumers. The area of interest is the tidal turbine and its support structure fully submerged in high-density flow seawater. A typical site for a tidal current energy device is a challenging environment

Oil and gas operators and their suppliers reported skills shortages in the key occupations of geologists geophysicists and subsurface-reservoir engineering. Sub-sea UK also reported deficiencies for highly qualified and experienced engineers. The lead-time to 'produce' an appropriate individual (right technical degree additional expertise etc) for the operator and sub-sea sectors requires long-term planning based on sound information and intelligence. The objectives of the research were to: understand the key factors which contribute to identified problems of the availability of people to carry out jobs-roles in geology geophysics and sub-sea engineering; evaluate the current provision within the learning supply chain; capacity; capability and current action; assimilate information from employers and learning providers such that recommendations can be made to improve agreed issues and challenges. The findings are reported and recommendations are made.

The new Freon-free international standard for oil-in-water analysis EN ISO 9377-2 was formally accepted in October 2000. The method is described. External calibration is used for quantification. The technical robustness of the new method is examined. This has been demonstrated through a number of validation studies and by inter-laboratory exercises. The historical robustness is also addressed. The method has been recommended by the Norwegian State Pollution Control Agency as the new reference method for oil-in-water. OLF (the Norwegian Oil Industry Association) and IMO have tested the method and suggested it for the analysis of discharges from oil-producing platforms in the North Sea and for the analysis of discharges from ships (bilges). Further discussions are going on in OSPAR about the possibility of including volatiles and monoaromatics (BETX) in the same analysis. The problem is where to set the lower limit of the method related to the hydrocarbon boiling point and also the need for detecting aromatics (including polyaromatic compounds) by more specific methods (GC-MS). Certified oil-in-water samples may be available in the future through an EU project that will be initiated in 2002.

Advances in underwater networking will accelerate if researchers are able to re-use software frameworks and interfaces to the physical layer as is done in terrestrial cabled and wireless networking. The most common development paradigm in use today is custom-written software that is normally not available to others to use as a starting point. In addition network researchers that develop software targeted at a specific physical layer may have difficulty porting network software to other modems if the interface is not generalised with a driver to create a generic device. A modular open-source software architecture has been developed and demonstrated for simple ad-hoc networks. While the initial implementation includes and uses an interface to the WHOI Micro-Modem the system is intended to be device-independent in order to allow network researchers to write code that can be run on multiple hardware platforms. Its main function is to provide an architecture that allows easy plug-in of specific link-layer functions such as MAC (medium-access control) and modem-specific physical layer interfaces. An in-depth overview of the software architecture and its mapping to network functionality is included plus initial results of a simple ad-hoc network created as the initial implementation example. While time will tell if this will be successful this first step is key to starting a process that will involve multiple institutions and projects and advance the state of the art in underwater acoustic networking.

Limitations in our current knowledge of a ship in extreme wave conditions have been illuminated by the work being done by the US Navy on advanced hull-forms. Stochastic approaches to these phenomena are insufficient and deterministic testing of these events must be carried out if the physics is to be understood. Although modern computer controlled wavemakers provide the ability to generate regular sine waves long crested multi-spectral waves mixed seas of almost any sea spectra and even 'freak' waves all of these systems require the wavemakers be tuned to the specific facility and that transfer functions between wavemaker settings and the generated wave be calculated. This tuning is carried out to compensate for the facilities geometry wave absorbers (beaches) etc as well as to aid the researcher in using the wavemaker system. The MASK (manoeuvring and seakeeping) basin at the NSWCCD (Naval Surface Warfare Center Carderock Division) is a large rectangular basin measuring 240 feet (73.2 m.) by 360 feet (109.7 m.). Two adjacent walls of the MASK are equipped with pneumatic wavemakers while the other two banks are equipped with wave absorbing beaches. This paper describes the development of a feed-forward neural network model of the MASK wavemakers and demonstrates the utility of this approach in calibrating wavemakers and generating wavemaker transfer functions.

A study was set up to examine the inter-relationship between water-quality determinands and to identify the spatial controls upon water quality at a regional scale. The study was to help fill a research gap of a regional river study in Hong Kong to provide a basis for contamination-abatement and to help formulate a better management plan for the local river environment. A six-year river data water quality set obtained by the HKEPD (Hong Kong Environmental Protection Department) at 82 monitoring sites was used to study at a regional scale the spatial controls and influences upon water chemistry in HK rivers. Univariate statistics and factor analysis of the elements were applied to analyse 27 determinands of surface water quality. The results are presented and discussed. The statistical results show that nutrients aggregate organics and metals have greater variation than physical parameters which are less influenced by anthropogenic factors. These determinands can also be explained by four principle factors representing nutrient and organic contamination marine influences and heavy metal contamination. Finally the local rivers can be classified into four groups based on the factor scores derived from the factor analysis. These results may contribute to the improvement of land-use planning and sewerage design in the future.

Spar platforms have been in service in the Gulf of Mexico since 1996 for combinations of production workover and drilling applications. They resemble a cylinder and when exposed to a steady current shed vortices from one side to the other resulting in pressure oscillation which causes VIM (vortex-induced motion. VIM has serious consequences on the fatigue of mooring and riser systems and suppression is achieved through helical strakes which disrupts the formation of vortex. At present there is no analytical means of predicting the effectiveness of strake design other than resorting to long and costly experiments conducted in model basin. An alternate approach is explored which uses numerical methods in CFD (computational fluid dynamics) currently being investigated by many researchers. Investigation of this approach is presented here by comparing the transverse vibration of a spar (truss spar) selected from the direction which produced the largest vibrations in the experiment for a range of currents. This approach is well suited for flows where small scales transmit a notable amount of energy to larger ones. The flow simulation is compared with experimental data from a model test.

The use of fixed stator blades either upstream or downstream of the propeller has been recognised as a means of reducing the rotational losses behind a propeller thereby yielding a higher propulsive efficiency. The use of ducted propellers has often been an attractive alternative for ship and underwater vehicle propulsion as well. Ducted propellers have been used both to protect the propeller and to increase propulsive efficiency or to reduce propeller cavitation. A method is developed to analyse the flow around a ducted propeller operating in combination with a set of pre-swirl stator vanes. The method uses a boundary element method to solve the flow around the duct and the hub and a lifting surface vortex lattice method to solve the flow around the propeller and the stators. The 3D flow around the duct-hub propeller and stators is computed separately with the interactions between them being accounted for in an iterative manner. The interactions between the duct and the stators and between the duct and the propeller are treated in a non-axisymmetric manner. However only the circumferentially averaged interactions between the propeller and the stators are considered. Using this method a duct and set of stators are designed to operate efficiently with an existing propeller. This model was then built and tested in the MIT water tunnel at a variety of stator pitch angles. Comparisons are made between the theoretical and experimental values for the forces on the duct propeller and stators. A very good agreement is achieved in the region of attached flow.

Recreational boating in the US has undergone tremendous changes during the past 50 years both quantitatively and qualitatively. The number of boat registrations has increased together with the type of boats and the boating activities. There are basically two reasons why these developments have resulted in a demand for new and more relevant navigational charts and other aids to navigation. Firstly the nations Small Craft Navigational Charts should reflect the diversity of boating activities which require additional information that is generally not readily available on the charts developed and distributed by NOAA's Marine Chart Division. Secondly and perhaps more importantly the increase in the number of boats has begun to stress the coastal and near-shore marine environment. Examples of this include increased manatee mortality sea grass scarring discharge of waste materials overboard (although this is now prohibited) increased powerboat speeds inappropriate anchoring practices. An initiative is reported to identify the information that small-craft charts can convey to enable safe navigation and to promote environmental stewardship. The methods and findings related to the following two project objectives are discussed: to determine whether additional chart information would result in increased safe navigation and environmental stewardship; and to determine whether chart information needs vary with the type of boat owned and the respondent's education.

The wedge wave-make is and has been a topic of interest to hydrodynamicists. The analysis of the performance of a wedge-type wavemaker in a tank of finite depth is presented. The analytical technique is somewhat different to those applied previously to performance studies of wave-makers. Those techniques included the assumption of a product solution of the Laplace equation which lead to combinations of sinusoidal and hyperbolic functions of the wave number. In the technique described here both product and summation solutions are assumed. This assumption is based on the fact that the fluid beneath the wavemake is confined by the wave-maker the back wall and the tank floor. From potential-flow theory the streamlines of the oscillatory flow of this confined fluid are well defined. In a 3D analysis of hydrodynamic coefficients of a heaving vertical circular cylinder Yeung (1981) makes this assumption without stating so. Using the experimental data of Wang (1974) for comparison results of the analysis are presented for various combinations of wave-maker draft breadth and water depth for a triangular wedge. The results show that the effects of the evanescent waves are of second-order. Close to the wedge results are presented resulting from the inclusion of four evanescent waves. The technique is of value because of its relatively simple form and its versatility.

The Snorre TLP has been operating in the Northern North Sea since 1992. During the last year an extensive reanalysis of tether tension TLP motion and airgap has been carried out in order to ensure that the TLP can withstand updated environmental conditions and design requirements. The aim of this paper is to describe the analysis methods which have been used to determine extreme tether loading and to compare analysis results with model test results. The model tests were carried out in the facilities at MARIN in the Netherlands and considered more than 200 three hour realizations of irregular seastates with and without wind and current. Typical fatigue seastates as well as extreme 100 year and 100000 year seastates were investigated for both head and quartering seas. The extensive database of model test results gives an opportunity to study the accuracy of the analysis methods. The analysis of the TLP response was carried out in the time domain using the SIMO software developed by Marintek. In the work described here the results from a purely linear radiation-diffraction analysis is used as the main load model in SIMO together with slender element additions based on the incident wave kinematics.

The accuracy and resolution of sediment bulk density measurements are examined. Bulk density from cores is traditionally measured by weight loss of extruded and sectioned 2-cm-thick sediment disks. The actual bulk density is thus an average value for the volume of a 2-cm-long-x-cross-sectional-area sediment core disk. Thus the values of the measurements as well as the estimates of the correlation lengths may be a function of the disk thickness (sampling interval) and estimation of correlation lengths may be distorted. From a bulk density power spectrum and correlation length estimated from existing data Monte Carlo realisations of the density were obtained for the sediment volume. From such realisations the same procedures used in the actual core analysis on the simulated cores were reapplied to obtain a 'virtual' bulk density profile and then re-estimated the power spectrum. Because actual density is known from the original data in the simulation the difference between the parameters used to generate the simulation and the 'virtual' parameters is a measure of the distortion. As a result of numerous simulations run to achieve a robust estimate of 'virtual' bulk density it is shown that laboratory procedures bias (lower) the actual variance of the parameters by averaging or smoothing. In related work however the first-order auto-regressive approach for estimating correlation length from contiguous disks indicates a bias toward a higher value of the parameter than is appropriate.

Today's MBES (multi-beam echo-sounders) provide detailed bathymetric information that allows local slope corrections to be made to the concurrently collected acoustic backscatter imagery thus improving seabed characterisation possibilities. Although the data is available local-slope corrections are not typically applied in the backscatter-processing scheme. An approach is presented that compensates backscatter for local slope by taking into account vessel yaw pitch and roll angles when determining the beam incident angle at the sea floor and using all the available closest neighbour soundings within a certain radius. The normal of the 3D local curvature at each beam location is then calculated by a weighted least squares fit to the surrounding surface. The proposed method can use all the available geometric information from co-registered depths and backscatter strengths either from a single survey line or multiple survey lines if overlapping lines exist. These grazing angle computations lead to estimates of the sonar's transmitting and receiving beam patterns and their deconvolution from the backscatter data to extract seafloor property information in regions of complex topographic relief. This technique is applied to a backscatter image created from data collected on the mid-outer continental shelf off the New Jersey Margin with a Simrad EM100 multi-beam sonar system. Backscatter data normalisation with the computer grazing angles yielded a better correlation between the independently measured grain size and backscatter data than that obtained with non-normalised backscatter data. 87933

Ideas from using bio-inspired locomotion concepts for robotic underwater applications are presented. The technology of land-based bio-inspired walking robots has improved a lot in the last ten years. For example systems like The SCORPION Rhex or DANTE II have proved that high mobility in rough terrain can be achieved. Walking is a locomotion technique that can be found in underwater animals such as lobsters crayfish or prawn. These animals can be found in the littoral zone of the oceans and rivers which is a very challenging environment. Crayfish and prawn can also live in rough terrain like the slope of a black smoker. They are especially able to adapt to irregular ground contours currents wave action and surge. For example lobsters can navigate around obstacles such as rocks crevices and seaweed. They flourish in the benthic and littoral environments and have developed robust control systems for locomotion sensing and searching behaviour. These control systems therefore present a solution. No artificial wheeled or swimming system is able to navigate as robustly as lobsters or crayfish in such underwater environments. Studying the behaviour of animals in the littoral zone and using their control principles for robots would seem to be a promising way to close this gap. Past research in this direction was analysed (for example the ARIEL and the NEU Lobster project) and new ideas based on our existing systems are proposed for a robust underwater walking platform. A possible control concept for such an underwater walking system is proposed. Possible application scenarios are discussed100285